updated res/triangleSize/meshCellSize behavior towards a more correct
solution

* renamed triangleSize to meshCellSize
* made bounding box derivation depend on meshCellSize
* made meshCellSize private parameter of TileSpec with default 64 that gets
  serialized with the TileSpec, meshCellSize has no public setter except
  through bounding box calculation, existing bounding box can be reused if
  requested for the current meshCellSize, otherwise recalculate
* added meshCellSize as optional query parameter to coordinate and tiledb
  web services, default 64 is used when left out